Physiological responses to gradual drought stress in the diploid hybrid Pinus densata and its two parental species |
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Authors: | Dahai Gao Qian Gao Hai-Yan Xu Fei Ma Chang-Ming Zhao Jian-Quan Liu |
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Institution: | (1) Key Laboratory of Arid and Grassland Ecology, Institute of Molecular Ecology, School of Life Sciences, Ministry of Education, Lanzhou University, 730000 Lanzhou, China;(2) Key Laboratory of the Qinghai-Tibetan Plateau Ecological Adaptation, Northwest Plateau Institute of Biology, Chinese Academy of Sciences, 810001 Xining, Qinghai, China;(3) Key Laboratory of Arid and Grassland Ecology, Lanzhou University, 730000 Lanzhou, China |
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Abstract: | Pinus densata is a homoploid hybrid species, originating from P. tabuliformis × P. yunnanensis. The physiological fitness of this natural hybrid compared to its two parental species remains unknown. In this study, we
investigated physiological responses of the three species by exposing artificially breed seedlings of each to drought stress
lasting 28 days. Our results suggest that, in all three species, drought affected the contents of the plants’ chlorophyll,
stomatal conductance, TBARS, hydrogen peroxide, and free proline and increased the activities of antioxidant enzymes, including
superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), and peroxidase (POD; EC 1.11.1.7). The drought stress
also induced significant changes in the activity of ascorbate peroxidase (APX; EC 1.11.1.11), monodehydroascorbate reductase
(MDHAR; EC 1.6.5.4), dehydroascorbate reductase (DHAR; EC 1.8.5.1), glutathione reductase (GR; EC 1.6.4.2), and levels of
ascorbate and glutathione in the ascorbate–glutathione cycle. The hybrid species P. densata appeared to achieve greater drought tolerance and exhibit hybrid superiority in antioxidant processes and other related physiological
traits compared to the two parental species, although a few of the hybrid’s measured variables were similar to those of P. tabuliformis. However, P. yunnanensis was more sensitive to drought and appeared to have the lowest resistance to such stress. These physiological differences
are largely consistent with the species’ habitat preferences, which may reflect their early genetic divergences and niche
differentiation. These findings provide important information for management and forest restoration efforts of these species
in the future. |
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Keywords: | Drought Physiological fitness Antioxidant respond Hybrid superiority Pinus densata |
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